Pyrane bskivaiwes



United States Patent 5,tl74,% PYRANE EERWATEVES:

Johannes Donates you Mihusch-Buchherg, liambnrg- Hashing, Germany, assignor, lay mesne assignments, to Unilever Limited, London, England, a company oi England No Drawing. Filled Aug. 23, 1958, der. No. 757,657

Claims priority, application Great Britain Aug. 30, T257 2- -llainrs. (Qt. sea-sass This invention relates to pyrane derivatives and provides new derivatives of oxo-pyrane and new methods for preparing such derivatives.

The pyrane derivatives of the present invention are oxopyranes having attached to each of four ditlerent carbon atoms of the heterocyclic ring an acyclic hydrocarbon group, two of the acyclic hydrocarbon groups containing 1- to 20 carbon atoms and the other two acyclic hydrocarbon groups containing 2 to 21 carbon atoms, the pyrane derivatives having two carbon to carbon double bonds apart from any within the acyclic hydrocarbon groups.

The acyclic hydrocarbon groups may be saturated or unsaturated and branched or unbranched. In the derivatives of most interest both carbon to carbon double bonds are in the ring but the invention includes derivatives in which least one of the double bonds is between the ring and one of the hydrocarbon groups, that group being an enyl group.

- Of particular importance among the oxo-pyrane derivatives of the invention are gamma-pyrones of the formula:

C (011 B) ORLC OCR C (CH IFL? where R, R R and R are acyclic hydrocarbon radicals containing 1 to 20 carbon atoms. R, R R and R are preferably identical, but may be different.

isomers of these pyrones include alpha-pyrones of the formula:

and derivatives with double bonds connecting one of the hydrocarbon groups (an enyl group) to the ring such as:

and derivatives with double bonds connecting two of the hydrocarbon groups to the ring such as:

G O.CHR.C (EH3 .CHR C CHRWO and ' o enmcnnaooonnaoeonnoo 3,6743% Patented den. 22, tees acid with weak or volatile bases such as zinc borate and ammonium pentaborate; and organic boron compounds such as esters of boric acid and mixed anhydrides of bone acid and organic acids, for example boric acid trimethyl ester, boric acid triethyl ester, boric acid mannitol ester, the mixed anhydride of boric acid and acetic acid and the mixed anhydrides of boric acid and higher fatty acids. Borax and oxidising boron compounds such as perborate are less suitable.

The process may be carried out at normal or reduced pressure. The reaction mixture may be kept at the boiling temperature of the mixture and carboxylic acid distilling off may be condensed and returned to the reaction mixture after removal of water. Alternatively a solvent of appropriate boiling point may be used. The solvent, when used, is partly distilled off together with any water liberated, condensed, separated from the water and may be returned wholly or in part to the reaction mixture.

After completion of the treatment any residual acid or acid anhydride may be removed, for instance by distillation and the residue freed from catalyst, for instance by washing with water. 1

The acids that can be employed (as such or in the form of their anhydrides) in the condensation include: unbranched paraftinic mouocarboxylic acids, such as propionic, butyric, Valerie, caproic and oenanthic, caprylic,

. capric, lauric, myristic, palmitic and stearic acids, branched parafiinic monocarboxylic acids such as pivalic and isocaproic acids, and olefin monocarboxylic acids such as 4-hexenoic, oleic, linoleic, and erucic acids. Acids with terminal unsaturation such as vinylacetic acid tend to undergo polymerization unless suitable precautions are taken. 1

The invention includes using mixed anhydrides of two acids of the formula specified.

Diketones for use in making the pyrones include for in-' stance, 4-methyl-hepta-3z5 dione, 5-ethyl-nona-4z'6-dione, 6-prc-pyl-undeca-5 7-dione, 7-butyl-trideca-6 2 S-dione.

When R is an unsaturated hydrocarbon group care should be taken to avoid polymerization as much as possible. Polymerization mostly occurs when the degree of unsaturation is too high.

The oxo-pyranes of the invention provide new intermediates for use in organic syntheses, new plasticizers, and new cutting oils. For these purposes the compounds in which the hydrocarbon radicals are saturated are particularly useful. The oxo-pyranes in which one or more of the hydrocarbon radicals contains at least two double bonds have drying properties and are useful as vehicles for paints, varnishes, etc.

The products of the invention are colourless crystals, or more or less viscous liquids according to their molecular weight, with a colour varying from light yellow to pounds of an acid nature, i.e. capable of forming esters,

or anhydrides by reaction with -OH or -C0.0l-l groups, during the reaction. They include: inorganic boron compounds such as boric oxide, boric acid, and salts of boric brown. They show an increased iodine value as compared with the diketones, acids, or anhydrides used as starting materials, owing to the two extra double bonds formed in or near the pyrane ring during condensation. The gamma-pyrones and some of their isomers are 1111- saponifiable; others, including aipha-pyrones are saponifiable, but, probably owing to the presence of the four hydrocarbon groups on the pyrane ring, to a smaller extent than alpha-pyrone itself.

The invention will now be illustrated by the following examples, wherein all the parts are by weight. 1

Example 1 10 parts of 7-butyl-trideca-6:S-dione were heated with 16 parts of caproic acid anhy'dride and 2 parts of boric oxide at atmospheric pressure for 1 hour at 250 to 260 C. and then for 3 hours at 270 to 300 C. Caproic acid was distilled off and the higher boiling compounds refluxed by means of a fractionating column mounted on ,ehloride testt j thereaction vessel. The temperature was then lowered 1 to 200 C., the pressure reduced to below 14 mm. and

the reaction mixture fractionated at temperaturesrislng from 200 to 350 C.. Besides caproic acid "(1 1.2 parts) a' main fraction (9.9 parts) boiling at 235 C under a pressureof '14- m m. wasobtained. This was composed mainly lof 2 6-dipentyl-3 5-'dibutyl-gamma-pyrone.

. Example 2 A-mixtureof 13.4 parts of7-butyl-trideca-6:S-dione, 5.8 parts of-caproic acid and '09 part of boric oxide was heatedfor two hours at boiling temperature at atmos- Ph ric pressure in a reaction vessel fitted with a fracti'onating column. 5.8 parts of 'caproic acidwere then added and the reaction mixture was keptboiling I for another 7" hours onan oil-bathkept at a temperature of t 270 to 3 1 .C. During this time the temperature of the reactionmixture remained somewhat below 250 C( The temperature of the fractionating column was .regu lated in such'a way that' the water of reaction was dis-- tilledTofi butthecaprdic acid returned to thereaction mixture.

"After the heating the-reaction mixture was distilled- V Fraction (dyconsisted m ainlyaof 2:6-dipentyl 3 :5-

dihutykga'rnm'a-pyrone with a subsidiary amount of and iodine value 134.4 and saponification value 6.4. In the same manner, linoleic acid anhydride can be condensed with its corresponding diketone, heptatricontaisomers. N0 trace ofthe 7-butyl-trideca-6: 8-dione ini-' tiallyused could be 7 7 Example 3 l The reaction mixture was of the following composition:

1 mol: T of 4-methyl-heptadione-3 :5. 2 mols.. o f propi'onic anhydride. 0.5?mol. of boric oxide;

' Thismixturewas heated under reflux to 220: 'C. and

thetemperature was then graduallyraised while distilling offi: ca'proic acid formed; in tlie reaction to a temperature of250itC. 'in-thezco urse' of 4* hours; The pressure was" thenireduced to 101mm; and a further amountrof propioriic-aeid-- distilled 01f.v From thexresulting reaction rnixtureraafraction: composed mainly of 2? 6-diethyl-3z5- dmietliylagamma pyronezand isomers-distilled over be tween t1a40;and 150 C. This fraction was" saponified and the unsaponifiable matter, consisting/off about 65% was j recrystallized-repeatedly from pentaneii 7 *Itahad the following characteristics:

Aeichval-uera a i O "'Saponification'value '0- Melting pointtcolourless needles) .38.5 C. Moleculat weight? 180 I V RefractiveindexatfiOf C 14990 Example 4 e Theiniti-alreactionmixture was as follows;v

nyl-ltlzZOi-dion'e.

1 mol. of oleic anhydride. ,QES m'oL of. boric oxide.

5 f Thegreaction mixture was heated under a pressure of 5 .m mQto 280i.C;andthetemperature was maintained washingwith hot water. The ,residue was composed of heptatricontaz10-28z29 dienvl9-hexadecfound-by means of the usual ferric enyl-gamma-pyrone.

Example 5 The initialrea'ction mixture had the following composition:

1 mol. of 9-hexyl-heptadeca-8:IO-dione. 2 mols of caprylic anhydride; 0.5 mol. of boric oxide.

This mixture was heated as in Example 1 and the product was then fractionated under a pressure of 1 mm. The fraction boiling at 215 to 245 C. was composed mainly of 2:6-diheptyl-3:S-dihexyl-gamma-pyrone and isomers. It was a light'yellow coloured oily liquid of refractive index l'Z =1.4828 and molecular weight of 458 and a saponification. value of 54.

What isclaimed is:

1. 2:6-diheptadec-8:9-enyl'- 315 a dihexadec 7":8-

2. 2:6-di-heptadec-8':9-1l:12'-dienyl-3:5 dihexadec- 7" 8"-10: 1l-dienyl-gamma-pyrone.

3. Process for preparing substitution derivatives of substances selectedifrom the class consisting of alpha pyrone and gamma pyrone which comprises: (a) forming a mixture of an agent selected from the group consisting of monocarboxyli'c acids of the formula RCH -COOH and 'anhydrides thereof with a beta-diket'one of the for group consisting of borie oxide, boric acid salts of weak bases, boric acid salts of volatile bases,- boric' acid esters,

and mixedanhydrides of boric acid and a monocarboxylic acid, (c) removing theYwater liberated in the reaction as it is formed, and (d) recovering from the reaction mixture a fraction composed substantially of the pyrone v derivative.

4. Process for preparing a pyrone derivative which comprises: (a) forming a mixture of a beta-diketone of the formula R-CH COCHRCO-CH R with a substance 7 selected from the group consisting of RCH -COOH and the anhyclride thereof in which R represents the radical hexadec-7:8s-enyl-, (b) heating said mixtureiat a temperature of 220 to 350 C. in the-presence of borie oxide, (0) removing water liberated in thereactionas it is formed, and (d) recovering from the reaction mixture a fraction composed substantially of the pyrone derivative.

\ References-Cited in the file of this patent Kaushal et. aL:

Bh'agwat et. aL: Chem; 'Abst, vol. 41, page 1917 (1947).

- 'C'a'valierz' Chem;Reviews, vol. 41, pages 525 584 Chem.- Abst, vol. 40, page 5723 

1. 2:6-DIHEPTADEC-8'':9''-ENYL-3:5-DIHEXADEC-7":8"ENYL-GAMMA-PYRONE.
 3. PROCESS FOR PREPARING SUBSTITUTION DERIVATIVES OF SUBSTANCES SELECTED FROM THE CLASS CONSISTING OF ALPHA PYRONE AND GAMMA PYRONE WHICH COMPRISES: (A) FORMING A MIXTURE OF AN AGENT SELECTED FROM THE GROUP CONSISTING OF MONOCARBOXYLIC ACIDS OF THE FORMULA R-CH2-COOH AND ANHYDRIDES THEREOF WITH A BETA-DIKETONE OF THE FORMULA 